Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B1/00—Percussion drilling
  • E21B1/38—Hammer piston type, i.e. in which the tool bit or anvil is hit by an impulse member
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D17/24—Damping the reaction force
  • B25D17/245—Damping the reaction force using a fluid
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B44/00—Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
  • E21B44/02—Automatic control of the tool feed
  • E21B44/06—Automatic control of the tool feed in response to the flow or pressure of the motive fluid of the drive

Definitions

• the present invention relates to a device and a method for controlling an impulse-generating device for drilling in rock.
• the invention also relates to an impulse-generating device.
• a drilling tool In rock drilling, a drilling tool is used that is connected to a rock-drilling device via one or more drill string components.
• the drilling can be carried out in several ways, a common method being percussive drilling where an impulse-generating device, a striking tool, is used to generate impacts by means of an impact piston that moves forward and backward.
• the impact piston strikes the drill string, usually via a drill shank, in order to transfer impact pulses to the drilling tool via the drill string, and then on to the rock to deliver the energy of the shock wave.
• the impact piston is typically driven hydraulically or pneumatically, but can also be driven by other means, such as by electricity or some form of combustion.
• Impulse-generating devices in which the shock wave is generated by an impact piston have the problem that the forward and backward movement of the impact piston results in dynamic acceleration forces that have an adverse effect on the impulse-generating device (the striking tool) , and thereby the whole rock-drilling device.
• a feed force is used to press the rock-drilling device, and thereby the drill string and drilling tool, against the rock in front of it, in order to avoid the harmful reflections that can arise if the drilling tool is not in contact with the rock at the time of the impact.
• An impact piston that is accelerated in the direction of the impact gives rise, however, to counter forces in the opposite direction that act to move the rock-drilling equipment in a backward direction, away from the rock.
• impulse-generating devices In an attempt to reduce the problem of th acceleration forces of the impact piston, impulse-generating devices have been produced in which the shock v ave energy is not transferred by a piston that move forward and backward, but instead by pre-loading an impact element by means of a counter-pressure chamber whereby pressure impulses are transferred to the drill string by means of the impact element by a sudden reduction in the pressure in the counter-pressure chamber
• this solution generates shock waves with lowe energy, and, in order to maintain the efficiency of the drilling, the lower energy in each shock wave is compensated for by the shock waves being generated at a higher frequency.
• a control device for an impulse-generating device for inducing a shock wave in a tool, with said impulse-generating device comprising an impact element for transmitting said shock wave to said tool, a counter-pressure chamber acting against the impact element and a device for reducing the pressure in the counter-pressure chamber.
• the control device comprises means for controlling the reduction in pressure in said counter- pressure chamber.
• the means for reducing pressure can include a control valve for connection to said counter-pressure chamber, with the control valve comprising at least one opening for controlling said reduction in pressure by the release of the pressure medium contained in the counter-pressure chamber during operation.
• the reduction in pressure can be controlled by controlling the opening of the control valve.
• the control valve can be designed with pressure-reducing notches for controlling the reduction in pressure. This has the advantage that the reduction in pressure can be controlled in a simple way.
• the counter-pressure chamber can comprise a plurality of outlets, with said outlets being able to be opened in a controlled way. The outlets can have different diameters. This is so that the reduction in pressure can be controlled in a simple way by the opening and closing of the appropriate outlets.
• the outlets can be connected to one or more reservoirs by means of one or more flow paths, which said reservoirs can be pressurized during operation to different pressures, whereby a stepped and/or continual reduction in pressure in the counter-pressure chamber can be obtained by opening said outlets.
• the invention also relates to an impulse-generating device according to Claim 12.
• Figure 1 shows a schematic cross section of a control device for an impulse-generating device according to a preferred embodiment of the present invention.
• Figures 2a-2e show examples of shapes of shock waves and reflection waves.
• Figures 3a-c show an example of a control device according to the present invention.
• Figures 4a-b show another example of a control device according to the present invention.
• Figure 5 shows an additional example of a control device according to the present invention.
• Figure 6 shows yet another example of a control device according to the present invention.
• Figures 7a-d show examples of different impulse- generating devices that can be used together with the present invention.
• Figure 1 shows an impulse-generating device 10 for a rock-drilling device that can advantageously be used with the present invention.
• the device 10 is connected to a drilling tool such as a drilling bit 11 via a drill string 12 consisting of one or more drill string components 12a, 12b.
• a drilling tool such as a drilling bit 11
• a drill string 12 consisting of one or more drill string components 12a, 12b.
• energy in the form of shock waves is transferred to the drill string 12, and then from the drill string component 12a, 12b to the drill string component 12a, 12b and finally to the rock 14 via the drill bit 11, for breaking the rock 14.
• a piston that moves forward and backward is not used to generate the shock waves, but instead a loadable impact element in the form of an impact piston 15 is used, which is urged towards the end of a housing 17 that is opposite to the drill string 12 by the effect of a pressure medium acting against a pressure area 16.
• a chamber 18 is pressurized via a control valve 20 so that the pressure in the chamber 18 acts on the pressure area 16 and thereby urges the impact piston 15 towards the rear end 19 of the housing 17.
• the chamber 18 thus acts as a counter-pressure chamber.
• the control valve 20 is then opened suddenly to create an immediate reduction in pressure in the counter-pressure chamber 18, whereupon the impact piston 15 expands to its original length and transmits potential energy to the drill string 12 in the form of a shock wave.
• This sudden reduction in pressure generates a shock wave of essentially the same shape as a shock wave generated by a normal impact piston, that is a principally rectangular shape, see Figure 2a, which propagates through the drill string to the drill bit 11 for transmission to the rock 14.
• Figure 2b shows an example of the penetrating force as a function of the penetration depth for an exemplary type of rock.
• the curve of the reflection wave can be obtained in a simple way by subtracting the penetration curve from the shock wave curve.
• Figure 2c shows the appearance of the reflection curve for the device according to known technology. As the penetration force of the drill bit is zero or essentially zero at the moment of impact, the amplitude of the reflection wave at this moment will, in principle, correspond to the amplitude of the shock wave. If the edge of the shock wave is very steep, as in Figure 2a, this thus means that the reflection wave will have a very high and hence harmful initial amplitude.
• the edge of the shock wave is considerably less steep in comparison with the shock wave in Figure 2a, for which reason, as shown in Figure 2e, the amplitude of the reflection wave is considerably lower in comparison with the known technology, and hence less harmful to the rock-drilling device.
• the rise time of the edge is precisely as long as the time that it takes for the drill bit to achieve maximal penetration. This time naturally varies, depending upon the type of rock that is being drilled, but if the type of rock is known, this knowledge can be used to select the rise time of the edge.
• the opening and closing of the control valve 20 is preferably controlled by a computer, and selection of operational data can, for example, be carried out by an operator entering suitable data into the control system of the drilling machine.
• the drilling machine can be provided with means for measuring/calculating the drilling rate automatically, and calculating the penetration time, and hence a desired value for the rise time of the edge, on the basis of these values.
• control valve 20 can act as a throttle valve, and can be arranged to directly control the opening by means of a controlled throttling.
• control valve 30 is designed as a throttle valve where the opening area in a main channel 31 can be freely controlled.
• Figure 3a shows the valve from the side, in a partially-opened state, where the left side of the main channel 31 is connected to the counter-pressure chamber 18 and the right side of the main channel 31 is connected to a reservoir (not shown) .
• a throttle slide 32 By controlling a throttle slide 32, the required opening area can be obtained, and the reduction in pressure in the counter-pressure chamber 18 can thereby be regulated by regulating the flow.
• Figures 3b and 3c show examples of how the opening area of the throttle slide can be designed.
• the area of the main channel 31 is circular, while in Figure 3b the opening 33 of the throttle slide is also circular and in Figure 3c approximately half of the opening 34 of the throttle slide is circular and approximately half is triangular.
• This design allows precise regulation of even very small flows.
• the edge of the shock wave can be shaped precisely as required.
• the length of the shock wave can also be controlled by generating a shock wave with a lower amplitude (that is keeping the pressure in the chamber at a constant level, for example a quarter or a half of the initial pressure) .
• the control valve 40 is provided with a pressure-reducing notch 41 in order to obtain a smooth regulation of the pressure.
• Figure 4a shows the control valve 40 from the side and Figure 4b shows the notch from below.
• the control valve 40 has an inlet 42 for connection to the pressure-reducing chamber 18 and an outlet 43 that leads to a reservoir (not shown) .
• the valve is provided with a valve slide 45 for opening and closing the valve 40.
• the valve is shown in its closed position, and when the valve is to be opened for the generation of a shock wave, the slide 45 is moved to the right in the figure.
• both the slide 45 and the valve housing 46 can be provided with notches.
• FIG. 5 shows yet another alternative embodiment of a control device 50 according to the present invention.
• the counter-pressure chamber is pressurized in the way described above, but the reduction in pressure is regulated by means of a different type of throttle.
• the counter-pressure chamber 51 comprises a plurality of outlets (five in the embodiment illustrated, but this number can, of course, be varied freely from two upwards) 52-56 that have a relatively small diameter.
• the opening of the outlets 52-56 can be controlled, whereby said reduction in pressure can be regulated by opening and closing suitable outlets 52-56. In the example illustrated, all the outlets have the same diameter, but the outlets can, of course, have different diameters.
• the different outlets 52-56 are connected to an essentially non-pressurized reservoir 57 and, by means of a suitable choice of diameters, the outlets 52-56 act as throttles, whereby a discrete regulation of the pressure can be obtained by opening the outlets sequentially or by combining sequential opening and opening in parallel.
• FIG. 6 shows yet another alternative embodiment of the present invention.
• the counter-pressure chamber 61 is provided with a number of outlets 62-64, but instead of being connected to a non-pressurized reservoir, these are each connected to a pressurized reservoir 65-67 respectively, with each reservoir 65-67 being pressurized to different pressures, and with all the pressures being lower than the corresponding pressure in a pressurized counter-pressure chamber.
• a continually or practically continually rising edge can also be obtained.
• This solution has the advantage that no energy is consumed by conversion to heat in a throttle process, as this energy is transferred in principle without loss to the pressurized reservoirs 65-67.
• Figures 7a-7d show alternative embodiments of impulse- generating devices that can advantageously be used together with the present invention.
• Figure 7a shows an impulse-generating device 70 with, in principle, the same function as the device 10 in Figure 1, but where it is possible to regulate how great a length of the impact piston is to be loaded.
• This is achieved by the impact piston being provided with flanges 71-73 behind which clamps 74-76 can be tightened in order to load a selected length of the impact piston lengths L1-L4.
• this embodiment thus also makes it possible to set the length of the shock wave in a way that does not affect the proportion of the energy that is wasted.
• Figure 7b shows an impulse-generating device 80, that also has, in principle, the same function as the device 10 in Figure 1, but where the impact piston 81 is subjected to a tensile stress instead of a compressive stress.
• the movement of the impact piston 81 is limited by a flange 82 and it is loaded by pressurization of a chamber 83.
• the chamber 83 functions precisely as the counter-pressure chamber 18 in Figure 1 and by regulation of the reduction in pressure in the chamber, the shape of the shock wave can be regulated as described above.
• Figure 7c shows an impulse-generating device 90 that functions completely in accordance with Figure 1, but where a pressure area 92 on the impact piston 91 is used to compress a compressible material 93 instead of loading the impact piston 91.
• Figure 7d shows an impulse-generating device 100 similar to that in Figure 7b, but where a compressible material 101 is compressed instead of the impact piston 102 being subjected to a tensile stress.
• the devices described above can also be provided with means for increasing still further the pressure in the respective counter-pressure chambers, after the pressurization of the chambers has been terminated.
• the pressure-increasing piston can also be used to increase still further the pressure in the compressible material in Figures 7c and 7d.
• a screw arrangement can also be used to increase still further the pressure of the compressible material by reducing the volume occupied by the compressible material by means of the screw arrangement, which thereby also increases the pressure in the counter-pressure chamber.

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• Engineering & Computer Science (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Physics & Mathematics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Mechanical Engineering (AREA)
• Earth Drilling (AREA)
• Surgical Instruments (AREA)
• Percussive Tools And Related Accessories (AREA)

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• 2005
  • 2005-05-23 SE SE0501149A patent/SE528859C2/sv unknown
• 2006
  • 2006-05-19 CA CA2608135A patent/CA2608135C/en not_active Expired - Fee Related
  • 2006-05-19 JP JP2008513404A patent/JP4769862B2/ja not_active Expired - Fee Related
  • 2006-05-19 EP EP06733418A patent/EP1885995A1/en not_active Withdrawn
  • 2006-05-19 ZA ZA200709769A patent/ZA200709769B/xx unknown
  • 2006-05-19 US US11/919,566 patent/US8051926B2/en not_active Expired - Fee Related
  • 2006-05-19 WO PCT/SE2006/000580 patent/WO2006126932A1/en active Application Filing
  • 2006-05-19 CN CN2006800180347A patent/CN101180451B/zh not_active Expired - Fee Related
  • 2006-05-19 AU AU2006250110A patent/AU2006250110B2/en not_active Ceased
• 2007
  • 2007-12-21 NO NO20076617A patent/NO20076617L/no not_active Application Discontinuation

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